A number of software-based systems are known in the art for the monitoring and analysis of VoIP networks. These include, by way of example, Chariot™ VoIP Assessor Version 1.0, commercially available from NetIQ Corporation of San Jose, Calif., and NetAlly™ VoIP, commercially available from Viola Networks of Somerset, N.J., formerly Omegon Ltd. Such systems typically monitor and analyze network-level VoIP performance in terms of quality of service (QoS) or compliance with service level agreements (SLAs), using packet-based measurements such as jitter, loss and delay.
Conventional monitoring and analysis systems such as those noted above exhibit a number of significant problems. One problem is that these conventional systems are often configured such that application-related effects can lead to mischaracterization of the actual contribution of the network to a given measurement. For example, the actual transmit time for sending out test traffic over the network in the conventional systems may be significantly delayed relative to its recorded transmit time if the endpoint device used to send the test traffic becomes busy with other processing tasks, thereby rendering the resulting measurements inaccurate.
Another problem relates to clock synchronization. Conventional techniques typically utilize a clock synchronization approach, in which the system attempts to synchronize the clocks of the endpoint devices used to perform a test, prior to taking any measurements involving those devices. Unfortunately, this approach is problematic in that clock synchronization takes an excessive amount of time, and thus unduly limits the responsiveness of the system to changing network conditions. Moreover, clock synchronization can fail altogether, since it depends on network conditions at the time the synchronization process is carried out, and these conditions may be unfavorable to accurate synchronization. Poor network conditions in a given segment of the network can preclude accurate synchronization of the associated devices, and as a result the system may be unable to analyze this network segment.
Other known network monitoring and analysis systems utilize a so-called “passive” approach which involves monitoring actual random call traffic over the network. This approach has very limited flexibility, in that it relies on actual call traffic generated by actual users rather than targeted traffic generated in accordance with specified test parameters.
The above-noted problems have been addressed recently by techniques described in U.S. patent application Ser. No. 10/261,431, filed Sep. 30, 2002 in the name of inventors M. J. Bearden et al. and entitled “Communication System Endpoint Device With Integrated Call Synthesis Capability,” the disclosure of which is incorporated by reference herein.
Despite the considerable advantages provided by the techniques described in the above-cited U.S. patent application Ser. No. 10/261,431, a need remains for further improvements in network monitoring and analysis systems.